
CHAPTER 4 PORT FUNCTIONS
User’s Manual U15400EJ4V0UD
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Table 4-1. Port Functions
Port Name
Pin Name
Function
Port 0
P00 to P07
I/O port. Input/output can be specified in 1-bit units.
When used as an input port, an on-chip pull-up resistor can be specified in 1-bit units by
means of pull-up resistor option register B0 (PUB0).
Port 1
P10, P11
I/O port. Input/output can be specified in 1-bit units.
When used as an input port, an on-chip pull-up resistor can be specified in 1-bit units by
means of pull-up resistor option register B1 (PUB1).
Port 2
P20 to P25
I/O port. Input/output can be specified in 1-bit units.
When used as an input port, an on-chip pull-up resistor can be specified in 1-bit units by
means of pull-up resistor option register B2 (PUB2).
Port 3
P30 to P34
I/O port. Input/output can be specified in 1-bit units.
When used as an input port, an on-chip pull-up resistor can be specified in 1-bit units by
means of pull-up resistor option register B3 (PUB3).
Port 5
P50 to P53
N-ch open-drain I/O port. Input/output can be specified in 1-bit units.
An on-chip pull-up resistor can be specified by mask option.
Port 6
P60 to P67
Input port
Port 7
Note 1
P70 to P73
Input port (only when input port is selected by mask option or port function register)
Port 8
Note 2
P80 to P87
I/O port (only when I/O port is selected by mask option)
Notes 1. Whether to use these pins as input port pins (P70 to P73) or segment outputs (S16 to S19) can be
selected in 1-bit units by means of a mask option in the
μPD789477, 789478, and 789479 or a port
mode register in the
μPD78F9478 and 78F9479 (refer to 4.3 (3) Port function registers and
CHAPTER 20 MASK OPTIONS).
2. Whether to use these pins as I/O port pins (P80 to P87) or segment outputs (S20 to S27) can be
selected in 1-bit units by means of a mask option in the
μPD789477, 789478, and 789479 or a port
mode register in the
μPD78F9478 and 78F9479 (refer to 4.3 (3) Port function registers and
CHAPTER 20 MASK OPTIONS).
4.2 Port Configuration
Ports have the following hardware configuration.
Table 4-2. Configuration of Port
Item
Configuration
Control registers
Port mode registers (PMm: m = 0 to 3, 5, 8)
Pull-up resistor option registers (PUB0 to PUB3)
Port function registers (PF7, PF8) (flash memory version only)
Ports
Total: 45 (CMOS I/O: 29, CMOS input: 12, N-ch open-drain I/O: 4)
Pull-up resistors
Mask ROM version
Total: 25 (software control: 21, mask option specification: 4)
Flash memory version
Total: 21 (software control only)